This application requests funds for the upgrade of our SPECT camera, which is used by several departments at Yale for NIH funded neuroimaging studies. The upgrade is requested because of deficiencies of our present device, including septal penetration in the collimator, camera breakdown secondary to dragging motion on the collimator, and a slow, outdated computer operating system. This upgrade would provide a state-of-the-art imaging device at less than half the cost of a new instrument. This camera has been and will continue to be a research-dedicated instrument that generates no clinical income. The CEIPE camera (Digital Scintigraphics, Inc., Waltham, MA) is a brain-dedicated device with a narrow gantry opening for the head. It has a solitary annular NaI crystal surrounding three mobile parallel-hole collimators. The high sensitivity and resolution (- 8mm in all three axes) of the device make it ideally suited dynamic imaging of multiple brain regions. Our Neurochemical Brain Imaging Program has played a significant role in the development, evaluation, and implementation of SPECTRA measurement-of neuroreceptor We are studying SPECTRA probes of the dopamine D2 receptor, the dopamine transporter, the serotonin transporter, and the benzodiazepine receptor. Our program was developed as a joint effort between the Departments of Psychiatry and Diagnostic Radiology (Nuclear Medicine). After the successful development and evaluation of tracers in monkey studies, we extended this research to healthy human subjects and subsequently to patients with a wide spectrum of neuropsychiatric disorders, including Parkinson's disease, epilepsy, schizophrenia, anxiety disorders, alcoholism, cocaine abuse, and Tourette's syndrome. The clinical studies have generated supportive collaborations with Neurology, Neurosurgery, and the Child Study Center. This research has successfully generated multiple NIH-funded projects that fully occupy 100% of the camera's time.